WordPress Language – FATAL error

I just set up a fresh WordPress system. I would prefer to have my system in my mother language (Icelandic) and thus became very interested when I stumbled upon the plugin WordPress Language. I follow the instructions, uploaded the plugin via FTP to the server but couldn’t get it to work. When I press the flag in the admin bar in the top region of the screen I get an error message something like this:

Then try posting in that plugin’s dedicated forum. These forums tend to have an average posting rate of 1 post every 10-15 seconds. Unless you post in the correct forum, the relevant plugin developers will probably never see your question.